1. Technical Field of the Invention
The present invention relates to methods and apparatus for electrospinning composite fibers comprising at least one polymer and at least one mesoporous material. The present invention also relates to a method of making a mesh or network of organic and inorganic fibers by electrospinning.
2. Description of the Prior Art
The electrospinning process involves the application of a strong electrostatic field to a capillary connected with at least one reservoir containing a conducting solution. Under the influence of the electrostatic field, a pendant droplet of the conducting solution at the capillary tip is deformed into a conical shape. If the voltage surpasses a threshold value, electrostatic forces overcome the surface tension, and a fine charged jet is ejected. The jet moves towards a ground plate acting as an electrode. The solvent begins to evaporate immediately after the jet is formed. The result is the deposition of thin fibers on a substrate in front of the electrode.
Electrospinning makes it relatively easy to spin continuous nanofibers from many different materials including, but not limited to, polymers. Electrospinning provides a straightforward and practical way to produce fibers with diameters ranging from few to about 2000 nm. These small fibers can support arrays of nanomachines and connect integrated arrays of nanomachines to larger scale systems.
U.S. Pat. No. 4,323,525, which is fully incorporated by reference herein, is directed to a process for the production of tubular products by electrostatically spinning a liquid containing a fiber-forming material. The process involves introducing the liquid into an electric field through a nozzle, under conditions to produce fibers of the fiber-forming material, which tend to be drawn to a charged collector, and collecting the fibers on a charged tubular collector which rotates about its longitudinal axis, to form the fibrous tubular product. It is also disclosed that several nozzles can be used to increase the rate of fiber production.
U.S. Pat. No. 4,689,186, which is fully incorporated by reference herein, is directed to a process for the production of polyurethane tubular products by electrostatically spinning a fiber-forming liquid containing the polyurethane. It is disclosed that auxiliary electrodes can be placed around the collector to help facilitate collection of the fibers. It is disclosed that the auxiliary electrodes can be arranged to facilitate separation or to prevent adhesion of the formed fibers.
The present invention relates to a method of making a network of fibers comprising polymer fibers and mesoporous molecular sieve fibers, by electrospinning. The network or mesh of non-woven fibers thus produced displays properties that are not present in the fibers prepared using only polymers or only mesoporous molecular sieves. The above mentioned references do not teach or suggest the production of polymer and mesoporous molecular sieve composite fibers. These composite fibers have numerous commercial applications including, but not limited to, use in sensors and biosensors, scaffolds for cell growth for artificial skin or bone, optical and electronic devices, nanotube composites, solar cells, fuel cells, smart textiles and paper. The electrospun polymer fibers discussed in the prior art cannot be substituted in place of the composite fibers used in the above-referenced applications. Thus, there is a need for developing electrospinning methods for producing composite fibers comprising polymers and mesoporous molecular sieves.